1. Field of the Invention
The present invention relates generally to digital x-ray imaging and, more particularly, relates to methods and apparatuses for two-dimensional dual-energy x-ray imaging.
2. The Prior Art
Recent advances in the field of semiconductor fabrication have resulted in the ability to fabricate large-format two-dimensional integrated detector arrays for x-ray detection. These detector arrays have on the order of millions of detector cells and provide instant acquisition of two-dimensional x-ray images with exceedingly high quality. The capability of these detector arrays will not be confined to providing only qualitative visual images, but also have great potential for quantitative imaging.
Dual-energy x-ray imaging is an accurate quantitative technique that can decompose a pair of subject images acquired at two energy levels into two images, each representing one material composition image of the subject. Current dual-energy x-ray imaging techniques are limited to using linear detector arrays. If dual-energy x-ray imaging can be further improved to use recently developed large format detector arrays, the capabilities of clinical x-ray diagnosis can be significantly enhanced. For example, dual-energy x-ray imaging could be used for improved diagnosis of breast cancer in mammography, for quantitatively predicting elderly bone fractures in bone imaging, and for improved diagnosis of pulmonary diseases in chest imaging.
There are two significant technological barriers for combining dual-energy methods and large format detector arrays together. First, the prior art dual-energy x-ray data decomposition methods are not suitable for use with large format two-dimensional detectors. The underlying reason is that current methods either require the user to make frequent judgments on a pixel-by-pixel basis in the process of data decomposition, or to use a mechanical device to exchange data interactively with the computer on a pixel-by-pixel basis. Such approaches are not suitable for analyzing data volume with millions of pixels per image frame. Second, large-format detector arrays are susceptible to substantial scatter distortions, whereas dual-energy x-ray imaging requires that primary image data be used.